I have done it 3 times one of my favourite races, everytime you do it you learn something about yourself. I did one lap and the camping at Van Gaalen a few weeks back trying to ease my foot back to health but seconded some friends who did 14, 16 and 18 laps. My personal record is 12 laps 9am-9pm.
The race is more about fueling than running. Carbo loading days before because you can't eat enough on the day, then high carb intake without filling your stomache. Roughly 30-50 carbs a lap, I mix my own which are 100g of carbs a sachet and have it over 4-5 laps, plus salt and vinegar chips, biltong, boiled potatoes, pretzels, bars, bananas etc.
Force down 500-750ml a lap and stay away from anything super sweet like GU.
The war I have is how much I can intake vs how sick I feel.
I try stay at 7 - 7.30 per lap which leaves like 10mins to feel like a human before starting again. You also need a base/tent where you don't have to worry sleeping, keeping your stuff safe and can refuel.
The wierd part is when it gets dark you feel refreshed until it runs out then a giant crash kicks in, my friends say 12am - 3am is really tough. Some guys do that for 3 days.